Method and device for the presentation of objects in surrounding space

ABSTRACT

The invention relates to a method device for displaying, in a way that is easy for an operator, such as a pilot in an aircraft, to grasp and understand, the direction to objects (A, B) in the surrounding space. In accordance with the invention the object is projected onto a projection surface ( 3 ) comprised of the envelope surface of a conical solid of revolution, where the operator is somewhere vertically (h) on the axis of rotation ( 2 ) about which the envelope surface ( 3 ) is created. Thereafter, the operator observes, on a display surface (I) such as a viewing screen, a plan view from above of the conical envelope surface, where the horizontal direction (c, d) to the objects, and each object&#39;s height (a, b) compared to one&#39;s own height (h), represented by a circular curve ( 6 ), are easily read.

TECHNICAL FIELD

The invention relates to a method and device for presenting information,in a way that is easy for an operator, such as a pilot in an aircraft,to grasp and understand, concerning the direction to objects in thesurrounding space. In accordance with the invention, the object isprojected onto a surface comprised of the envelope surface of a conicalsolid of revolution, where the operator is somewhere vertically on theaxis of rotation about which the envelope surface is created.Thereafter, the operator observes, on a display surface such as aviewing screen, a plan view from above of the conical envelope surface,where the horizontal direction to the objects, and the each object'srelative height are easily read.

STATE OF THE ART

It is a known fact that it is difficult to create a three dimensionalimage on a flat screen. It is, however, often necessary to provide anoperator, a pilot in a plane for example, with information about what ishappening in the surrounding air space. There are a number of solutionsthat use a flat screen to inform the operator about occurrences in thesurroundings. A known example is a so-called PPI, which with the help ofradar shows, on a flat screen, the distance and direction to a craft Inthis case, no information on the craft's vertical position is provided,important information for an observer in an aircraft Another example isthe case in which a pilot in a fighter aircraft receives information,through its own radar or other target seeker, on bearings and angle ofaltitude to foreign craft, whereby the craft is imaged as a point on aflat screen. The screen has both a horizontal and a vertical axes,whereby the position of the point to the right of the vertical axisgives the bearing of the craft to the right by up to 180°, while theposition of the point to the left of the vertical axis corresponds tothe bearing of the craft to the left by up to 180°. The position on thescreen of these points along the vertical axis corresponds to thealtitude of the craft, since the vertical axis represents a scale ofaltitude.

Commonly used nowadays, such a display on a screen may be difficult fora pilot to interpret A pilot, particularly the pilot in a fighteraircraft, has a range of instruments in his field of view, which meansthat in stressful situations interpretation of the instrumentinformation on the displays must be easily accessible and easilyconvertible to one's own conception of the world and of space.

The document U.S. Pat. No. 5,181,028 gives an example of a display forcommunicating information to a pilot on the position of nearby aircrafton a flat screen, where these are represented on a spherical gridtransformed to a plane projection. However, it is complicated to use, asapplication requires the use of means to stereoscopically read thedisplay.

DESCRIPTION OF INVENTION

One aspect of the invention is shown by the independent claims for themethod and the device. In accordance with this aspect, it is shown howone technically creates an image of surrounding space and the directionto objects in space for display on a plane display surface, for examplea viewing screen. The image of the surroundings is obtained by creating,about a reference position—normally one's own position, an imaginaryprojection surface in the form of a surface of revolution with avertical axis of rotation, where the cross-section of the surface ofrevolution increases in the direction from one end of the axis ofrotation to the other end. The height of the projection surface isarbitrary. In this description, the term cone is used to describe thesurface of revolution, since the surface of revolution can be eitherjutting inwards or outwards. The reference position in space is on theaxis of rotation, so that a horizontal plane through the referenceposition defines a circular curve on the projection surface, which showsthe height of the reference position. The height of the referenceposition refers here to the height of the reference position in the bodyencompassed by the projection surface. On measuring an object for whichone wants the direction shown on the projection surface, the position isdetermined for the point where a line of collimation from the referenceposition through the object intersects the projection surface.

It is now technically possible to image the direction to the object onthe projection surface, i.e. normally an instrument window, by showing aplan view of the defined projection surface, which, for example, can beembodied by the aforementioned cone, across its axis of rotation. Thedisplay surface shows a largest circle that denotes the largestcross-section of the projection surface, and a circle that representsthe height of the reference position projected on the projectionsurface. One's own position is represented by the center of the circle,where the axis of rotation of the projection surface is located. Thismid-point may be indicated by some kind of graphic symbol. From one'sown position, a reference direction, i.e. a zero direction, is definedon the circle defining the horizontal plane of the reference position.

Recording the object involves obtaining a direction to it, whereby bymeans of calculations, the position of the image of the object on theprojection surface is determined, and is entered as a point on the planeimage of the projection surface on the display surface. It follows thatthe said point, which is positioned on the line of collimation to theobject, will represent the direction to the object as seen from thereference point. If the cone is positioned so that its base is orientedupwards and the point lies outside the horizontal circle representingthe reference height, then the object is positioned higher than thereference position, i.e. the angle of altitude to the object ispositive. If the point in this case is below the horizontal circle, thenthe object is positioned lower than the reference height, i.e the angleof altitude to the object is negative. Moreover, the angle with the apexat the mid-point from the reference direction to the line of collimationto the object represents the bearing of the object relative to thereference position. It is preferable for the bearing to be counted fromthe reference direction, 180° to the right and 180° to the left, therebybeing intuitively in accord with one's conception of space. For example,an object on an instrument window that is imaged as a point lying on thehorizontal circle and 180° to the right or left is, therefore,positioned in a direction that is directly behind and at the same heightas the aircraft's own position in the case where the reference directionsignifies “straight ahead”.

The reference height, i.e. the height of the circular curve displayed onthe projection surface representing the horizontal plane of thereference position, may be either movable or fixed vertically on theprojection surface. These versions illustrate two different applicationsof the technique. In the case where the reference height is fixed on theprojection surface and the technique is used for a flying craftrepresented by the reference position, the projection surface followsthe aircraft is fixed to it. In the other case, when the referenceheight is movable, the horizontal circle will move vertically on theprojection surface in conjunction with any variation in the altitude ofthe aircraft. In the latter alternative, the circular curve, which showsthe horizontal plane of the reference position on the projectionsurface, will rise as the aircraft ascends from lower to higheraltitudes.

The described method and device can be used with advantage in aircraftto provide the operator, a pilot in this case, with an easilycomprehensible orientation of the direction to the object, such asforeign craft in the surroundings, viewed from one's own position, whichin this case is the reference position. The pilot can obtain, in a waythat is easy to grasp, angle information on these craft. This is a greatadvantage, since in this case a pilot has access to instrument systemsin the aircraft that are based on angle measurements, such as differentsensor systems, for example radar, IR sensors, and interceptionreceivers. If the pilot is to perform a cognitive or motor action, wherethe action involves an angle-related maneuver, it is much easier if theaction is supported by the method in accordance with the invention,since it only displays angles on the instrument window.

In accordance with the invention, the method and device can withadvantage be used within any field where the relationships betweenobject, occurrences and other phenomena can be described in accordancewith the aspect of the invention, such as in military and civilaircraft, Air Force Headquarters, simulators, operational control,process control, and surveillance systems.

DESCRIPTION OF DRAWINGS

FIG. 1 shows in a perspective view how different targets can be recordedfrom, for example, an aircraft, and how these targets can be representedby points on a conical projection surface.

FIG. 2 shows a plan view of the projection surface as in FIG. 1 andrepresentation of the targets on an instrument window, where thereference position is represented by the mid-point, the outer circle thelargest measurable angle of altitude to a target, and the inner circlethe horizontal plane through the reference position.

FIG. 3 shows in a sectional view the projection surface that is used inaccordance with the aspect of the invention.

FIG. 4 shows in a section through the projection surface the angles thatare the basis for calculating the projection of recorded objects on theprojection surface.

FIG. 5 shows how the display surface is linked to recording instrumentsand a processor for calculating.

FIG. 6 shows a display surface with only sectors of the surroundingsreproduced.

DESCRIPTION OF EMBODIMENTS

A number of embodiments of the invention are described below with theaid of the drawings.

In accordance with an embodiment of the invention, the aspect of theinvention is used to utilize instruments in an aircraft to recordobjects in surrounding space by reading the direction to the target, andby converting the measured values of the angle recording to the targetto a projection of the direction to the target as a point on aprojection surface 3. FIG. 1 shows from one perspective a referenceposition 1 in the form of an aircraft positioned somewhere vertically onthe axis of rotation 2 of an envelope surface shaped like a cone andrepresenting the projection surface 3. The cone's dimensions arepredetermined. For instance, the height of the cone's apex can beentered as zero; in other words, it is assigned to ground level. Theheight of the cone is arbitrary. When used in an aircraft, the height ofthe cone may be several thousand meters. It is also convenient to beable to switch between a number of fixed projection surfaces ofdifferent heights, i.e. in this case cones of different fixed heights.The width of the cone opening, i.e. its greatest circular cross-section,may be freely chosen. The size of the angle of altitude ν of the cone,which we have defined as the angle at the periphery of the circlebetween a radius in the said greatest circular cross-section and theapex of the cone, is arbitrary. Ground level, in this case sea level, isshown in the drawing with the land area indicated as symbols. Thecircular curve 5 around the largest cross-section indicates the largestangle of altitude that can be displayed on the projection surface fromone's own position, which here is the reference position 1. Anothercircular curve 6 represents the intersection of the horizontal planethrough one's own position and the projection surface. On the circularcurve 6, a point 0 indicates the direction forward from one's ownposition, in this case straight-ahead from one's own aircraft. Thispoint 0 is the reference direction and is used as the basis for statingthe azimuth, i.e. the bearing, to the target being measured, whichimplies that the bearing of point 0 is zero.

Two objects, in this case flying craft A and B, are drawn as targets inFIG. 1. The flying object A is diagonally behind and to the right ofone's own aircraft and at a greater altitude, i.e. with a positive angleof altitude α relative to one's own aircraft The azimuth c (see FIG. 2)to the target A, i.e. the bearing to A, is in the example measured as140° to the right, measured from the forward direction. The line ofcollimation from one's own position at 1 to the target A intersects theprojection surface 3, i.e. the cone, at point A1.

The flying object B is diagonally behind and to the left of one's ownaircraft and at a lower altitude, i e. with a negative angle of altitudeβ relative to one's own aircraft. The azimuth d to the target B, i.e.the bearing to B, is in the example measured as 120° to the left,measured from the forward direction. The line of collimation from one'sown position at 1 to the target B intersects the projection surface 3,i.e. the cone, at point B1.

FIG. 1 also shows the range of deflection that a sensor present in one'sown plane is able to span in space. This range of deflection isrepresented by 7 in the drawing. Such a sensor may be embodied by, forexample, an IR-sensor, which a pilot in the aircraft can maneuver bothvertically and sideways. In the example, the sensor is set for scanningof an area diagonally in front of and to the right of one's own positionand, in addition, at a higher altitude. In the example the sensor area 7is exemplified as spanning an angle of altitude between γ and δ andlaterally from bearing c₁ to c₂ to the right.

The direction to the measured targets A and B, and the position of thesensor area 7 are displayed on a display surface I, which may beembodied by a viewing screen (of CRT type) or some other form of display(e.g. LCD display) for displaying graphics. FIG. 2 illustates apresentation of a horizontal view, a plan view, of the space area aroundone's own position, which corresponds to the projection surface 3 inFIG. 1. In the presentation in FIG. 2, the shown circular curves 5 and 6represent angles. The circular curve 6 shows the height (on theprojection surface) of the objects that are at the same height as thereference position 1, i.e. in this case one's own height, while thecircular curve shows the maximum angle of altitude for which a targetdirection can be given from one's own position. One's own positioncannot be shown in the projection, since the projection surface 3represents the aforementioned envelope surface of a cone. Here you haveto imagine one's own plane positioned vertically on the axis 2 at thesame height as the circular curve 6. In the drawing, the distance mdenotes the maximum angle of altitude that can be shown on the displaysurface I using the selected projection surface. In the drawing, thetarget A is shown having bearing 140° to the right, with the angle ofaltitude α corresponding to the distance a above the circular curve 6for the projection A1 of target A. In the same way, target B isillustrated having bearing 120° to the left, with the angle of altitudeβ corresponding to the distance b above the circular curve 6 for theprojection B1 of target B. The sensor area 7 extends from bearing c₁ tobearing c₂ to the right, and from angle of altitude γ to angle ofaltitude δ, in this example showing positive angles of elevation.

Determination of the position of targets projected on the projectionsurface can be performed based on the angles and distances that areshown in FIG. 4, where a vertical section through the projection surface3 shows that the line of section through the envelope surface is astraight line. The line of section through the envelope surface couldequally well be a bent curve in the case where the envelope surface isdouble curved, i.e. the cone juts inwards or outwards. In the caseshown, the angle of altitude ν of the cone determines the slope of theprojection surface. The largest radius of the cone is denoted by R, theheight of one's own position by h, and the radius in the horizontalplane for one's own position by r. This data is known, since thedimensions of the cone are predetermined and one's own altitude h can beread from instruments. The angle of altitude to target A is α. It canthen be shown that the distance a, which corresponds to the distancehorizontally outwards from the curve 6 that is the projection of one'sown height on the cone, can be calculated as$a = \frac{r^{2}\quad \tan \quad \alpha}{h - {r\quad \tan \quad \alpha}}$

The distance a is governed by the angle of altitude α and, thus, can beconsidered a measure of the size of the said angle when shown on thedisplay surface I.

Similarly, the distance b represents the distance horizontally inwardsfrom the curve 6, where b may be calculated as$b = \frac{r^{2}\quad \tan \quad \beta}{h + {r\quad \tan \quad \beta}}$

and r=h/tan ν

FIG. 5 shows a couple of an arbitrary number of recording instrumentsM1, M2 for collecting data on angles of elevation and bearings tosurrounding objects A, B. This data is sent to a processor C, whichreceives information on the values of the required projection surfacevia a change-over switch 8. The processor C can then be supplied withpre-selected values for the desired total height of the projectionsurface, and its angle of altitude ν, as well as for the position of theapex of the projection above the ground surface. The cone-shapedprojection surface 3 may be turned so that its apex faces either upwardsor downwards. It is assumed here that the apex 4 is facing downwards,while the claims in this particular application are designed to coverboth alternatives. In the case where the projection surface mentionedabove is fixed to the aircraft, one's own height has, in this case, apredetermined value and has no significance as regards to height aboveground level.

Graphic representation of the direction to the object allows thedistance to the each of the objects A, B to be measured. These distancescan be represented on the display surface, in the form of a viewingscreen or display, by letting each object be symbolized graphically in away that is dependent on the distance to the object. This can beachieved by representing the different distances by, for example,different colors, different graphic symbols, varying sizes of thepicture elements, alphanumeric characters or a combination of thesegraphic representations. Therefore, in the case where action is requiredof an operator, measures can be employed according to the proximity ofthe object.

The display surface I can be embodied, as mentioned above, by a viewingscreen in the form of an ordinary television-picture tube, LCD displays,or be shown by means of VRD techniques (so called Virtual RetinalDisplay).

In many situations, one's main interest may be to study the surroundingsand obtain directional information for objects that are within aspecific sector, for example within the sector in front, i.e. betweenbearing 90° left and 90° right, here termed the forward sector. In sucha case, it is advantageous to show only a part of the forward sector onthe display surface, where advisably only a semicircle is shown. Thus,as shown in FIG. 6, a 160-degree section of the forward sector can bedisplayed to scale. The sector F indicted in FIG. 6 represents the160-degree forward direction, while display of targets present betweenbearing 80 and 180 right is shown compressed in sector R, at the sametime as targets present between bearing 80 and 180 left are showncompressed in sector L. In these sectors, R and L, the degree scale iscompressed. The intention is, nevertheless, to be able to indicatetargets in other directions even if one's attention is directed in aforward direction by having greater resolution in this sector. Othersectors than the ones proposed here can naturally be selected.

Measurements for the angles to the objects A, B can be obtained fromother measuring means than those mentioned above. Thus, the data in thecurrent example, where the reference position is held by an aircraft,can be obtained via links from, for example, the action informationcenter, some other flight information center or other external-measuringdevice. In these cases, the angle values to the objects are obtained byconverting externally received data by processing in a processor. Itfollows that at least one of the instruments M1, M2 in FIG. 5 cansymbolize such an external measuring device, which means, in thisexample, that processor C converts the obtained measurement data toangle values for the objects A, B relative to one's own position.

What is claimed is:
 1. A method for showing, on a display surface andfrom a reference position, the direction to surrounding objects inspace, wherein the angle of altitude and the bearing to the objects aremeasured, a projection surface in the form of an envelope surface of asolid of revolution having a vertical axis of rotation and across-sectional area which increases along the axis of rotation isdefined in space, where the reference position is located on the axis ofrotation, the horizontal plane through the reference position intersectsthe projection surface to form a circular curve, a line of collimationfrom the reference position to an object intersects the projectionsurface at a point, on the display surface, the projection surface isshown in a plan view across its axis of rotation, a reference directionis defined on the circular curve representing the horizontal plane, thedirection to the object in space relative to the reference position isgiven by an image of the position of the points on the display surface,where the bearing of the points from the reference direction gives thebearing to the object, and where the angle of altitude of the objectrelative to the reference position is represented by the distance fromthe points to the horizontal circular curve with a positive or negativeangle of altitude, depending on whether the point falls outside orinside the horizontal circular curve.
 2. The method according to claim1, wherein the reference position is movable along the axis of rotationof the projection surface.
 3. The method according to claim 1, whereinthe reference position is fixed to a certain point on the axis ofrotation of the projection surface.
 4. The method according to claim 2,wherein the apex of the projection surface follows the ground surfacelevel.
 5. The method according to claim 1, wherein measurement of anglesof altitude and azimuths to the objects is performed by radar, IR sensoror interception receiver.
 6. The method according to claim 1, whereinmeasurement of at least one of either the angle of altitude or theazimuth to an object is performed by a measurement device in a positionother than at the reference position, and that a processor converts thesaid angle so that they are related to the reference position.
 7. Themethod according to claim 1, wherein the reference position is occupiedby a flying craft, and that at least one of either the angle of altitudeor the azimuth to an object is received in the flying craft via a linkfrom a measuring device in another position, and that a processorconverts the said angle to values that are related to the flying craft.8. The method according to claim 1, wherein the distance to each objectis measured by distance meters, whereby the respective pointscorresponding to an object are symbolized on the display surface by agraphic symbol.
 9. The method according to claim 1, wherein on the planview of the projection surface on the display surface, only a part ofthe whole circle is shown.
 10. The method according to claim 9, whereinonly a part of the whole circle is shown by showing at least one sectorof arbitrary angle about the reference position.
 11. The methodaccording to claim 1, wherein the bearing for each object is displayedon the display surface as the bearing to the point corresponding to therespective object.
 12. A device for showing, from a reference position,the direction to surrounding objects in space, the device comprising:instruments for measuring the angle of altitude and bearing to therespective objects, a processor which is supplied with the said anglevalues and in which data is stored for a virtual projection surface inspace, where the projection surface is embodied by a surface ofrevolution having a vertical axis of rotation, and the cross-sectionalarea of the surface of revolution increases along the axis of rotation,with the reference position located on the axis of rotation, and wherethe processor calculates both the position of the point of intersectionwhere a line of collimation from the reference position to therespective object intersects the projection surface, as well as theposition of a circular curve which represents the intersection betweenthe horizontal plane through the reference position and the projectionsurface, a display surface that shows, in a plan view across the axis ofrotation, a) the projection surface in the form of a largest circularcurve, which represents the limiting curve of the greatest cross-sectionof the projection surface, b) a horizontal circular curve, whichrepresents the horizontal plane through the reference position and c)objects represented by the points.
 13. The device according to claim 10,wherein the processor calculates the distance between the horizontalcircular curve and the respective image points, where the distance is afunction of the measured angle of altitude to the respective objectsrepresented by the image points.
 14. The device according to claim 10,wherein the display surface is embodied by a television-picture tube, aLCD display, or a VRD image.
 15. The method according to claim 7,wherein the at least one of the angle of altitude or the azimuth to anobject is received from a flight information center or an actioninformation center.
 16. The method according to claim 8, wherein thegraphic symbol includes the point adopting different colors according todistance, the point changing size according to distance, the point beingdenoted by alphanumeric characters containing information regardingdistance, or the point being indicated by a graphic symbol together withan alphanumeric character.
 17. The method according to claim 10, whereinthe degree graduation of the shown sector is displayed in a scale ofone's choice.